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P-type Capacitance Observed in Nitrogen-doped ZnO

ZnO에서 질소 불순물에 의한 p-type Capacitance

  • Received : 2011.11.14
  • Accepted : 2012.05.16
  • Published : 2012.06.01

Abstract

We studied p-type capacitance characteristics of ZnO thin-film transistors (TFT's), grown by metal organic chemical vapor deposition (MOCVD). We compared two ZnO TFT's: one grown at $450^{\circ}C$ and the other grown at $350^{\circ}C$. ZnO grown at $450^{\circ}C$ showed smooth capacitance profile with electron density of $1.5{\times}10^{20}cm^{-3}$. In contrast, ZnO grown at $350^{\circ}C$ showed a capacitance jump when gate voltage was changed to negative voltages. Current-voltage characteristics measured in the two samples did not show much difference. We explain that the capacitance jump is related to p-type ZnO layer formed at the $SiO_2$ interface. Current-voltage and capacitance-voltage data support that p-type characteristics are observed only when background electron density is very low.

Keywords

ZnO;MOCVD;CV characteristics;TFT;Nitrogen;Display

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Acknowledgement

Supported by : National Research Foundation of Korea (NRF)